What do I eat?

Hello,

Seitan is a great source of protein, but if you are intolerant to gluten, you definitely should avoid this (it's made entirely out of wheat gluten!) I don't eat a lot of soy myself (occasionally Tempeh) so the next go-to protein source would be your lentils. Lentils have tons of protein compared to any other legume. Then of course, your black beans, chickpeas, etc. Beans and lentils also have high carb content.

I also wanted to mention Quinoa... I don't know if anyone had brought that up yet, but it is an awesome gluten-free "grain" that has lots of protein, too. Of the grains, it's a pretty good source of complete, amino-acid packed, protein. It's got about half as much protein as your lentils, but it's still an excellent option.
Lentils, rice, beans, quinoa... all great choices, and SATISFYING!

And then LOVE your vegetables. My go-to salad is simply spinach, tomatoes and avocado, with some almonds or walnuts. The avocado and nuts give you a good dose of healthy fats that keep you satisfied, and the spinach and tomato give you your carbohydrate and fiber sources to fill your stomach up. I also love sauteing vegetables in olive oil - my favorite combo recently is white onions, mushrooms, lemon and rosemary. Yum! I eat it by the bowl-full!

Here is a reference that I used a lot when I first became a vegetarian (and still reference today):
http://www.vrg.org/
All sorts of information on diet and nutrition.